


Heat Transfer

by orithea



Category: Sherlock (TV)
Genre: Alpha/Beta/Omega Dynamics, Alternate Universe - Boarding School, Anal Sex, M/M, Mating Cycles/In Heat, Omega John, Omega Verse, Teenlock, WIP
Language: English
Status: In-Progress
Published: 2013-08-19
Updated: 2013-08-19
Packaged: 2017-12-24 01:10:32
Rating: Explicit
Warnings: Underage
Chapters: 2
Words: 7,288
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/933339
Author URL: https://archiveofourown.org/users/orithea/pseuds/orithea
Summary: <blockquote class="userstuff">
              <p>When Sherlock Holmes is ten years old his brother goes into his first heat as an omega. Sherlock is determined that he'll do whatever he can to not have the same happen to him.</p><p>Until John Watson.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> When this story takes a turn for the explicit, Sherlock and John are both 17 years old, hence the underage warning.
> 
> Thanks to wiggleofjudas for the beta, and daleked for the encouragement!

It is the middle of the night when the noises start in Mycroft’s bedroom.

They’ve adjoining rooms, naturally, with their headboards both pushed against the shared wall. It was a necessary measure when Sherlock was a child with a rather vivid imagination, for whom every creak and groan of the Holmes manor’s settling floorboards was a potential threat. Mycroft taught him the tap code (“It’s been used since Ancient Greece,” Mycroft told him loftily. “And by pirates?” “Most pirates were illiterate, so I hardly think—” Mycroft stopped, seeing Sherlock’s glare, and sighed heavily. “Fine, then—yes. Used by pirates as well.”) Three quick taps, a short pause, four more taps against the wall by Sherlock’s head, another pause—slightly longer this time, then one tap followed by three more: “OK”—question implied. Always the same series of taps and pauses in response, spelling out “YES”, then, rather more firmly “GN”. The tap code wasn’t entirely necessary—Sherlock could certainly hear his brother biting out “good _night_ , Sherlock” after being disturbed one too many times during the night—but it became something of a ritual between them, one that still occurs now that they’re older (Sherlock is a very mature ten year old who no longer believes that there are _things_ roaming the halls at night, thank you) but with far less frequency.

The taps go unanswered tonight, and Sherlock could swear that Mycroft is groaning, except... it doesn’t really sound anything like him at all, though logic says that it must be. It sounds inhuman, like an animal in pain.

“Mycroft?”

No answer. Sherlock grabs the torch that he keeps tucked into his bedside table, switches it on, and pads cautiously from his bedroom into the hallway; he hesitates just a moment outside of Mycroft’s door, but when he hears that _sound_ again, he musters up his considerable courage and pushes the door open and sweeps the torch light in an arc across the bedroom, searching.

Mycroft is lying in bed, where he should be, but it’s immediately obvious that all is not well. The duvet and sheets have been kicked aside and are hanging down  to the floor, and Mycroft is curled tightly into himself, knees clutched against his chest. He’s naked—Sherlock noticed the exposure of pale, freckled limbs as the light passed quickly over his brother to settle on his face, which is set in a grimace, eyes screwed up and jaw clenched tight. It is obvious that the sound—now a low, pained whine—is coming from Mycroft.

“Are you ill?” Sherlock asks, torn somewhere between curiosity and concern.

Mycroft shakes his head furiously. “I don’t—” he begins, and is interrupted by a gasp.

Sherlock steps closer to the bed. “What’s wrong?”

“I need you to go get Mummy.”

“But why, what is—”

“Sherlock!” Mycroft snaps. “Now!”

Mycroft is never short with him. Sherlock would be hurt, go off and have himself a sulk, if it weren’t obvious from the way that Mycroft shakes, from the way that he sounds—nothing like his usual controlled self—that something is truly wrong. He scurries down the hall, wakes Mummy, and all but drags him back to Mycroft’s bedroom. Mummy flicks on the light, takes one look at Mycroft, and his face melts with concern.

“Sherlock, love, I need some time with Mycroft alone. Just for a while.”

“Is he okay?”

“He will be.”

\---

It’s hours later—the sun is up, and Sherlock’s had a few fitful hours of sleep—before Mummy slips into his bedroom and into the bed beside him. Sherlock wastes no time in letting his head fall into Mummy’s lap, and he is stroking curls away from Sherlock’s face within moments.

“What was wrong with Mycroft?” Sherlock asks through a yawn.

“You understand what presenting is?”

Sherlock nods—they’ve spoken about it at school, to prepare the children for its inevitability. Some alphas and omegas present as young as twelve years, and it’s typically considered better for everyone if they’re aware of the impending signs. “No one said that it was painful.”

“It isn’t painful for everyone. It is, unfortunately, for omegas.”

“Mycroft is an omega, then.” Sherlock frowns. The Holmes family did tend towards producing omega males, or so he’d been told. Still, he knew that Mycroft had hoped otherwise.

“He is, love.”

“And I probably will be as well?”

Mummy’s hand pauses in stroking his hair, and he sighs heavily. “There’s no way to be certain, but it does seem likely. But Sherlock, I promise that it’s not as terrible as you might think.”

\---

Sherlock’s not blind. He’s young; he may not understand _why_ people look at Mycroft the way that they do (why anyone would want to be bothered with all of the unpleasant business of heats and _breeding_ the way the textbooks describe it, Sherlock can’t imagine), but he observes. Sees the stares that increase exponentially after it’s revealed that Mycroft is an omega—eyes following him everywhere that they go together, so that suddenly Sherlock is no longer the Holmes child that grabs everyone’s attention. Sees the way they lean in closer to him, ostensibly attempting to catch a deeper inhalation of Mycroft’s matured scent (he smells the same as always to Sherlock—whether that’s due to his own immaturity or the fact that omegas never smell particularly strongly to each other, Sherlock does not wish to dwell upon). Sees the way that Mycroft shies away from the attention.

It’s Mycroft’s actions that weigh with Sherlock the most. In the wake of his first heat he’s done everything that he can to deflect this newfound interest. He takes scissors to his hair one evening, to Mummy’s horror, and never lets it grow long enough to curl again. He trades jeans and jumpers for suits worn like armor, even whilst finishing his studies at home with only tutors and family for company, commanding to be taken seriously. The way he loses weight—attributed to a late growth spurt by their parents, but Sherlock always has noticed more than they do—and takes care to carry himself carefully, poised, slimmed hips never swaying the way everyone says an omega’s ought.

“They called me such a pretty omega,” Sherlock heard Mycroft shout the evening that he cut his hair, and Sherlock fingered the hair curling over his own ears where Mycroft’s no longer did. After these careful affectations, the catcalls become rarer and rarer.

\---

Sherlock fights tooth and nail with Mummy and Father to be sent away to school. Reminds them that Mycroft presented relatively late, so he is likely to do the same; that boarding schools are _used_ to dealing with their teenaged charges and all that their hormones entailed; that the local teachers and tutors are, frankly, rather tired of him already; that it would be an utter waste not to send him somewhere that will make the most of his mind before it’s all derailed by biology. The last argument is perhaps the one that won over Mummy in the end.

The truth of the matter is that it would be next to impossible to hide his real plan if he remained at home. Too many keen noses and watchful eyes trained on him to miss the signs. He’ll need to be somewhere with more freedom—and he’ll need Mycroft’s help.

“I know about your suppressants,” Sherlock says. It didn’t take a genius to figure that one out. Mycroft is twenty years old, and after three years as an omega he remains unbonded and alone. He tells their parents that he’s being courted, but after a week of staying with him in his London flat, Sherlock can find no evidence to support that. Only one logical conclusion.

Mycroft narrows his eyes, sets aside the notebook he was writing in in order to give Sherlock his attention. “Not that it’s any of your business, but I did think that you might.”

“I won’t tell anyone.”

“And what do you want from me in return?”

“A supply.” Hormonal suppressants are difficult enough for an unbonded adult omega to obtain. For a thirteen year old who has yet to present, it’s nigh impossible.

Mycroft’s face twists into a grimace. “Sherlock, you can’t possibly expect to suppress yourself from ever presenting.”

“Why not? Just because no one’s done it?”

“Because you don’t even know if you’ll be an omega, for one, and because there’s no telling what it might do to your body. The hormones could easily have the opposite effect and shock your system. Cause a heat even earlier than it may have occurred naturally. If you are not an omega—” Mycroft shrugs helplessly. “Who even knows?”

“Mycroft,” Sherlock says his brother’s name with deadly seriousness, “if you had thought that you could possibly stop everything, all of this messy business, before it ever happened to you, wouldn’t you have taken the chance?”

Mycroft’s face hardens and Sherlock knows that he’s won; any further objections will simply be attempts to absolve himself from guilt. “If it does something to harm you—”

“It will be my own fault, not yours. Besides, what’s the worst that could possibly happen—either it speeds the process along, or it breaks something that I don’t want anyway.” When Mycroft does not respond, Sherlock presses further. “You know that I need to be somewhere else. Without you there I don’t have anyone; they all _hate_ me.” In truth, Sherlock doesn’t care at all about that, but he knows that Mycroft does on his behalf.

“Don’t think that I can’t recognise when I’m being manipulated,” Mycroft says coolly. “But I’ll do it. On the condition that you keep me informed.”

Sherlock can’t suppress a sneer.

“I’ll stop sending them if you don’t.”

“Blackmail? I would have thought that you were above that.”

“I will be when you are,” Mycroft says, eyebrow raised in challenge.

They stare at each other for a tense moment, but Sherlock is, for once, not fully committed to antagonizing his brother and breaks into a sincere grin. “I learned it from you.”

“Amongst other things that I sometimes regret having taught you,” Mycroft teases.

And, well, despite all insistence to the contrary Sherlock does care about Mycroft a great deal, misses how close they used to be before... before. A sudden surge of fierce protectiveness makes him ask, “Was it really that bad?” Having heats?”

“It’s enough that I’m willing to do this for you.”

Sherlock wants to ask more, ask what specifically made them unbearable, why Mycroft—always more conventional and worried about fitting in in ways that Sherlock simply can’t bring himself to care about—would do something so frowned upon, but Mycroft has picked up his notebook and pen again and Sherlock knows that’s the end of this conversation.

It must be terrible, and that knowledge only strengthens Sherlock’s resolve to never experience it himself.

\---

Boarding school isn’t quite everything that Sherlock hoped it would be. It turns out that other people are mostly the same everywhere: boring, tedious, criminally stupid, and too conventional to appreciate his particular intellect. He spends two years feeling increasingly alone, but not bothered enough by it to change his ways.

Until John Watson.

Sherlock leans across the aisle on the first day of their shared Chemistry class, where John’s sat beside him for half an hour and spoken all of twice. It’s enough to make a deduction, and the fact that Sherlock’s caught the other boy glancing over at him several times compels him to share it. “Afghanistan or Iraq?” he asks, just loud enough to get his attention.

“What?” John says, startled and loud enough that the professor sends a sharp look in his direction that makes John sink down in his chair until he turns his back again.

Sherlock, who had immediately snapped back into place at his own desk after asking the first time, leans over again. “Your father—Afghanistan or Iraq?”

John shoots a surreptitious glance towards the front of the room before leaning towards Sherlock. “Afghanistan. How did you know?”

“Your accent is a muddle, which says you’ve frequently moved from area to area. Your haircut and posture, combined with your obsessively neat dress—which could be chalked up to it being your first day here, but point towards something else when considering the whole package of your appearance—suggest a military upbringing. You’ve only just started here this year, which means that something has happened to necessitate a change in schools. Those facts together, it’s likely that your father deployed; Afghanistan and Iraq were the most likely options.”

Sherlock smirks when he sees John look down at himself and compare his clothes—neatly pressed shirt tucked into his pants, tie knotted with care and pulled snug, jacket mostly buttoned—with those of the other boys, who’ve had two years to grow tired of uniforms and become increasingly rumpled and as far off regulation as they can be without receiving demerits. Sherlock himself didn’t bother with his school tie at all today.

Experience says that will be the end of the conversation. John surprises him by defying expectations. “That’s amazing,” Johns says, and he actually sounds as though he means it.

“Watson!” the professor barks out. “Something you need to share with the class?”

“No, sir,” John mumbles, and keeps his face firmly trained on his notebook for the remainder of the class period.

So begins a long tradition of Sherlock causing trouble and John being caught for it.

\---

Three hours after meeting each other, John’s gone and punched someone who walked by and called Sherlock a freak whilst they ate lunch together, and Sherlock knows they’ve just become friends. He brings John an ice pack for his knuckles when he’s let out of detention that evening, and they stay up talking together most of the night, so that John oversleeps and is nearly late for his first class the next morning.

They make a striking pair, Sherlock knows. He’s all long, gangly limbs; pale skin and dark curls he can’t be bothered to do much with. When they met, he and John were nearly the same height, but Sherlock gets taller whilst John stays the same. Well, not exactly the same—John may be small, but rugby and football give him plenty of compact muscle (and leave him more tanned and sun lighten the dark blond of his hair). People notice them together.

Their friendship is a funny thing, something unusual that Sherlock feels the need to push the boundaries of, run experiments on to see what makes it tick and how far he can go. John is remarkably patient with everything that Sherlock throws his way, including sneaking into John’s bedroom and waking him at three in the morning to make him join in a card game with a group of boys that Sherlock suspects are stealing from Mrs Hudson, the housemistress of the girls’ dormitory; smoking cigarettes whilst hanging partially out of John’s bedroom window; using John’s bed when he finally decides to give into the all too human need for sleep, whether John happens to be occupying it at the time or not; and other general violations of John’s personal space. Not that John is a complete pushover; he has a spectacular temper when it’s been set off, and Sherlock is very slow to learn what it actually takes to provoke him.

Usually— _usually_ —an explanation is enough to garner forgiveness, but the few occasions when John’s effectively locked him out of the room with a chair wedged under the door handle, Sherlock stands in the hallway and plays his violin until John relents and lets him into the room, muttering about everyone in the bloody building getting the wrong idea.

(Is it the wrong idea? Sherlock never asks.)

They mostly don’t talk about gender—unusual when it’s sometimes all their peers seem _capable_ of talking about, and every time someone presents it’s gossip for weeks. They get the basics out of the way early on, because the first time John hears about a boy going into heat he’s a strange mix of curious and horrified, and Sherlock realises that he’s not used to the concepts at all.

“Both of your parents are betas? God, I thought betas were lucky to have one child, let alone two.”

“Oi, don’t let my sister hear you—she’s punched people for less.”

Sherlock snorts. He’s never met Harry Watson, but he’s heard enough stories about her crusade for beta equality (a response to all the rudeness and outright hatred she experiences as a female beta in a relationship with a female omega) to believe it. “That’s what they always tell us, though. That alphas and omegas have the best hope for producing children, whilst betas seem to simply stumble into reproduction.”

“You lot have a really twisted idea of what betas are like, you know. Not everything in the world revolves around alphas, omegas, and... heats.” John pulls a face of distaste. “We’re actually the majority of the population, these days. Maybe not in the circles you’re used to,”— _in this school_ is implicit in his tone—“but in most of the world.”

 _We_. John assumes he’ll be a beta like his parents, his sister, the majority of his family for generations. He doesn’t live with the threat of presenting and having his body rebel against him completely hanging over his head, not like Sherlock. For that reason, Sherlock doesn’t confide in him about the suppressants—he has the feeling that John, who thinks he takes poor enough care of himself as it is, wouldn’t quite understand the dread that Sherlock feels at the thought. John seems rather indifferent to the gender of others, anyway. Sherlock’s seen him chat up people all across the spectrum: mostly beta females, though there was Victor Trevor, whom John had to be well aware was omega, and even Sarah Sawyer once. (“She’s an alpha,” Sherlock told him, because she had presented before John came to school and Sherlock didn’t always trust him to figure these things out for himself. “I know—i—it’s not like that, I mean,” John stammered, and Sherlock could have sworn that he was blushing.)

If Sherlock sometimes stops to consider that if he _had_ to choose someone for all of this messy biological business it would be John—John who actually values Sherlock’s ability to observe, who accepts his flaws with minimal complaint, who would never force him to become some sort of brood omega—he doesn’t dwell on it. It’s a moot point. He’ll continue with his suppressants, because that’s worked for Mycroft, and John can take care of all those... other things with someone else.

Sherlock doesn’t think of how much imagining John doing those things with someone else twists him up inside.

 


	2. Chapter 2

The first indication that something is wrong is when John returns from rugby practice, flops down onto his bed, then immediately rolls over to his side to face Sherlock, who sits on his floor attempting to study for A-levels (a process that mostly involves making faces at the textbook for being full of such unnecessary information). “Biscuits,” John demands.

“Which ones?” Sherlock asks, feeling blindly for the desk drawer.

“The chocolate ones.”

“Think I ate those...”

“Oh, you complete wanker. Fine. What’ve we got?”

Sherlock finds a pack of HobNobs that have been languishing away for ages because Mrs. Hudson gifted them to Sherlock, and neither of the boys are particularly fond of them. Not that you’d know it to look at John, who tears into the package as soon as Sherlock tosses it into his hands and eats like he hasn’t in days.

“Rough practice?” Sherlock deadpans.

“You’ve no idea,” John says around a mouthful. “The lads were piling on me like you wouldn’t believe—damned near crushed me more than once. Why d’you ask?”

“Because you seem to have worked up an appetite, and you _reek_.” Sherlock can smell him across the room. Not an unpleasant smell, exactly, but far stronger than typical for John.

“Do I?” John pauses his eating, ducks his head down to sniff himself, then shrugs. “I took a shower before I came back.”

Obviously true; his hair is still damp. Strange, then. Sherlock shrugs it off.

John wads up the now-empty packaging and lobs it towards the trash. “Christ, I’m still starving. Dinner early tonight?”

Sherlock considers. He’s not particularly hungry, but he’s also not interested in sitting here on the razor’s edge of boredom either. “Fine.”

John gives him a hand up and they walk to the dining hall together, where John proceeds to eat three plates piled high with a bit of everything from tonight's menu whilst Sherlock pokes at his pasta. He’s not entirely disinterested in the food, but he’s far _more_ interested in what’s happening to John at the moment. Because Sherlock has not spent the past seven years since his older brother’s first heat, living in fear of his own, without learning to recognise the signs of oncoming oestrus. The slight increase in scent and ravenous appetite are suggestive, but not certain, until—

“My skin feels like it’s on _fire_ ,” John complains once they’re back in his room again. “I’ve never noticed the tag on this shirt before, but it’s driving me mad.” He strips his uniform shirt off and pulls his pajama top out of the wardrobe. It’s just a thin cotton tee shirt, worn soft from countless washings, but John almost immediately strips it off again. “This is odd,” he says, looking at it in confusion. “It’s like I’ve got a rash or something.”

“John.” Sherlock says his friend’s name with low gravitas that makes John look at him with concern.

“Yeah?”

“You might want to sit down, because this is going to sound strange.”

John frowns at him, but sinks down onto the mattress. The action pulls a groan from his lips, and then he’s on his back, stretched out on the sheets. “God, this feels amazing.”

“Focus,” Sherlock says sharply.

John sounds distant, distracted. “What?”

Better to get it out before he’s completely incapable of paying any attention. “You’re going into heat.”

“What?” John repeats, but he’s snapped back upright and is staring at Sherlock, open mouthed.

“Presenting,” Sherlock clarifies. “As an omega.”

“Yeah, I fucking know what heat means, ta. But I’m not—” John lets out a nervous laugh. “That’s impossible. I’m a beta; I’m not—”

“You _are_. Apparently.”

“How can you tell?”

Sherlock gives him a look that he hopes fully articulates what a stupid question that is. “The eating—that’s your body trying to store up energy before it properly starts. You said that they kept piling on you in the rugby scrum, which was undoubtedly due to that smell you’re starting to put off, even if it wasn’t quite strong enough for any of you to realise just yet. Your skin’s becoming more sensitised; there’s no rash, but fabrics that you did find acceptable will become increasingly grating.”

“But I haven’t—it’s not...” John flushes with embarrassment.

“The lubrication comes later. With increasingly painful contractions.”

As if to reinforce Sherlock’s words, the first pain hits John’s guts and he falls to his back again and curls into a ball waiting for it to pass. When he can speak again, John’s voice is small and tired. “What do I do?”

“Ah, well—” Sherlock’s knowledge didn’t quite cover this point. He knew the options, but how to present them to his best friend, for whom the whole thing was entirely unexpected, and have him choose was another matter. “You could do it alone. That’s mostly a waiting game—your first heat, shouldn’t be more than a day or two. Frustrating, but there’s no complications. Or you could,” Sherlock’s chest feels tight and he has trouble getting out the words, “you could spend it with someone. You’ve got plenty of beta friends. Alphas too.”

“No,” John insists. “No, I’m not getting knotted in my first bloody heat, so that’s right out.” John sighs deeply and squeezes his eyes shut, face screwed up in intense displeasure, and just for a moment Sherlock thinks he might begin to cry—he’s seen John do it before, hot tears of frustration sliding down his cheeks at his angriest. Instead, John takes another deep breath and clenches his hands, before pounding a balled up fist against the mattress. “ _Fuck_ , I can’t believe this is even happening at all.”

“I’m sorry,” Sherlock says, and he means it. As much as he’s never wanted this for himself, he’d never wish it on John either, never thought it was even a possibility that he might present omega. “There’s still the option of a beta. I’m sure one of your rugby mates would be happy—”

John cuts him off. “I don’t want any of them to see me like this. I don’t want _anyone_ to see me like this. I’m going to be vulnerable and I’ll be panting for it, and I don’t _trust_ anyone to see me like that and not think differently of me.”

Sherlock nods, because that’s it, that’s it exactly. If it were him, if he were the one going into heat, the only person he would trust in that moment would be John.

“Except—” John sits up and reaches out to Sherlock, who’s been keeping careful distance under the assumption that the last thing John would like right now is to be touched, and grabs his wrist to pull him close. “There’s you. If I trust anyone in the world, it’s you, Sherlock.”

Sherlock stares at him, speechless.

“I know it’s a lot to ask and I completely understand if you don’t want to because we’re not... you’re not even interested in that sort of thing, but if it’s going to be anyone, it’s you. I’ll take care of it by myself, otherwise.” John looks up at Sherlock imploringly, still seated on the bed so that Sherlock towers over him.

It’s not exactly true that Sherlock isn’t interested. Just that the desire to do something messy involving genitals and mouths and _feelings_ with anyone—with John—is overridden by an even stronger desire to not go through the very thing John is at the moment. But if their situations were reversed, John would take care of him, and Sherlock knows it. There’s nothing that he wouldn’t do for John in turn—not even this. “Okay,” Sherlock says, and John’s relief is instant, leaving him smiling for the first time since the conversation began. “I just need to get some things from my room.” Sherlock takes a step towards the door.

“Wait, where—” John’s grip tightens on Sherlock’s wrist, hard enough to bruise as he tries to prevent his friend from leaving.

“For God’s sake, I’ll be right back. We’re not doing this without supplies.”

John looks sheepish and lets go of his wrist. “Sorry. Hormones. Making me needy, you know.”

“I know. I promise, I will come straight back. Just... try to take a nap or something.”

“Sleep is the furthest thing from my mind right now,” John says with a wry bark of laughter. It turns into a groan as another spasm hits him. Sherlock winces in sympathy, but takes the opportunity of John’s distraction to slip from the room.

\---

When Sherlock returns two hours later, John is in bed, but he’s not managed to fall asleep, as predicted. Instead he’s removed the rest of his clothing and he’s stretched naked over the sheets. He’s on his back and his hand—his left hand, Sherlock’s brain supplies helpfully—is between his legs. The rumpled sheets obscure John’s fingers from view, but the wet sound that follows when he jerks his hand away from himself as Sherlock enters the room hardly requires Sherlock’s keen observational skills to identify.

“Sorry, it’s just—” John’s voice is low and full of shame, and he looks away from Sherlock as he yanks the sheet over himself. “It’s started. The... leaking.”

If it were anyone else, Sherlock would probably be disgusted. It is disgusting, isn’t it? But it’s John, and John has a tendency to be interesting where other people aren’t. Sherlock drops his bag by the door and takes a seat in his customary spot on the floor by John’s bed. “Don’t be sorry. You can’t help it.”

John ignores that he’s spoken and continues to talk over him, though he does sit up, hugging his knees to his chest, to look down at Sherlock. “Christ—you know, Murray told me that he was with an omega girl once and that the slickness was amazing, and I was always thought I would love to try that, but it’s an entirely different thing when it’s happening to you and coming out of your _arse_. And I’m burning up. Everything is too hot. I’d open the window, but...”

“Yes, best that you don’t,” Sherlock agrees. He can smell the scent that’s rolling of John in waves now, rich and sweet like skin musk and spiced honey, and not at all unappealing for all that it doesn’t drive him to pin John to the mattress and climb inside him the way it might do for any alpha who caught a whiff of it right now.

“The worst thing is that I’d probably welcome whatever happened,” John mutters.

“Of course you would,” Sherlock says. “It’s biology. We’re designed that way. But you don’t have to worry about it.” He motions towards the bag that he brought back from his room. “Toys. They’re my brother’s,” Sherlock explains. “He gave them to me in case—” In case his experiment in forever rejecting the possibility of being an omega happened to fail, which is not something that he wants to confide in John just yet.

“In case this happened to you,” John finishes for him.

“Yes. You don’t have to use them, but they’re there. It’s an option.”

“It’s—” John pauses, licks his lips, and Sherlock can see that he’s started to tremble. “If it’s all right with you, I don’t think I want anything like that. Not just yet.”

“Ignoring what your body wants isn’t going to make this any less awkward.”

“I know that,” John snaps. “I just want to retain some fucking dignity until I can’t ignore it any more, okay? You don’t know what it feels like, losing control like this.”

Sherlock scowls and pulls a textbook into his lap to bury his face into and ignore John until he feels like being reasonable again.

The room grows quiet. John must be resolutely gritting his teeth through his pains—his breathing speeds up, becomes harsh pants at irregular intervals before growing calm again. There is the occasional sound of the sheets rustling as John stirs restlessly against them, but he doesn’t cry out. The near-silence is finally interrupted by a soft whimper, followed by a long gasp. When Sherlock looks up to investigate, John is on his stomach, arm contorted behind him to slip the tips of two fingers inside himself.

“I can’t—I need it,” John whispers, and he whimpers again.

Sherlock gets up and approaches the bed cautiously. “What do you need?”

“More. This isn’t enough. I need more.” The words tumble out and Sherlock knows John’s far gone if he’s willing to beg. And Sherlock doesn’t think he’s exactly interested physically—his body isn’t responding to seeing John splayed open and wanting across the bed the way that it would if he were an alpha, or even a beta—but intellectually, he’s fascinated by seeing omega’s heat first hand. It’s a preview of what he’s likely in for if he ever stops the suppressants, and he’ll know for sure if it’s possible for an omega to be satisfied through heat without being knotted. Because if he and John could do this together—

Sherlock’s pulse is thundering when he kneels on the bed over John and shoves John’s hand out of the way to replace John’s fingers with one of his own.

“Oh,” John says through a long, shaky exhale. “Oh _fuck_.”

Even if Sherlock were entirely unfamiliar with omega anatomy, he would be sure to unerringly slip in just where John needs him. The lubrication trickling out of John is warm and slick and it eases the passage of his finger as it slides inside, but it’s nothing compared to the feeling that lights up his nerve endings as he pushes further into John, exploring the anterior wall until his fingertip grazes John’s prostate and breaches into his vaginal aperture. It’s like finding the secret, molten core of him, and there is a hot and liquid squeeze around Sherlock as John arches his back and cries out at the intrusion.

“Your fingers weren’t long enough to reach,” Sherlock deduces.

“No,” John says unsteadily. “No, not like yours.” There is a short pause as though John is still too shy to keep asking, but need wins out. “Another.”

Sherlock pulls out, then pushes two fingers back in together. It’s a tight squeeze and John’s body is clenching around him so hard that Sherlock can’t really imagine how _more_ could possibly fit, but the backwards cant of John’s hips can be instinctually read as a plea for just that. So Sherlock curls them in and out, dipping teasingly into the spot where John wants the pressure the most, then adds a third and a fourth finger as well.

With three fingers dipping into his hidden entrance and a fourth just brushing over his prostate below, John starts to writhe. His mouth falls open, his eyes are screwed shut, and the sounds falling from his mouth could easily be mistaken for agony by anyone who couldn’t feel him needily grasping around their hand. The way that he wants this, wants _Sherlock,_ is gorgeous. Just completely fucking gorgeous.

Sherlock’s prick is throbbing where it’s still trapped inside his clothes.

“John”—Sherlock’s voice is breathless, reverent—“did you know it would be like this?” Part of his brain protests that it’s a stupid question—of course John didn’t, because he had no reason to expect that he’d have to know the first thing about omega heats, wouldn’t have done the research. Sherlock was under the impression that the whole thing was a horrible business, because why would Mycroft suppress his heats if they were anything but intolerable? This is beyond his expectations. He’s never responded to anyone, anything, like this before.

John can’t speak; he just shakes his head furiously, and a broken whine escapes him as he presses back on Sherlock’s fingers.

“Good, though?”

“It’s—” John trails off, panting, as he tries to find the words. “It’s amazing, and not enough at the same time. Like nothing could never be enough.”

Sherlock is slow to respond as he considers. “Nothing? Or just not my fingers? Because I could—”

Before he can finish his sentence, John cuts him off. “Please,” John keens. “Please, Sherlock. God. Just... please.”

The toys are right there waiting, in the bag by the door. Sherlock should get them. He doesn’t want to.

What he wants, like he’s never wanted anything before, is to shed his clothes so that he can press his own skin against every heated inch of John’s, to kiss him, to rut against him, to slide his erection inside of the tight heat now enveloping his fingers and fill John up the way he’s begging to be filled. He hasn’t felt this way since he was thirteen years old and felt the first stirrings of _something_ inside himself and took the only measure he could conceive of to put a stop to it, and even then it wasn’t directed towards another person. Now he wonders what he was so afraid of. John is fine; this is good, and they will be _so_ good together.

Sherlock works his fingers free—it will have to be done no matter what comes next—which pulls a string of unhappy and desperate noises from John. “No,” he says, half sob. “No, no you can’t take them out, not yet.”

“Shh,” Sherlock tells him with a gentling stroke of his free hand across the small of John’s back. He wipes his wet fingers on the sheets, already sodden with the fluid leaking slowly and steadily down John’s thighs. “I’m not stopping. Just turn over.”

John scowls, perhaps the most like himself he’s acted in hours, and looks as though he’d like to protest the necessity of having to do anything like moving—anything other than having this incessant need to be _full_ satisfied. To coax him, Sherlock bends down and lets his lips brush along John’s neck and up to his ear, and employs the rumble of his deep voice—something he’s only beginning to understand the full power of—to his advantage. “It will be worth your while.”

There’s just a momentary hesitation; John licks his lips, shudders, then rolls over.

Sherlock moves between John’s legs as soon as he’s on his back. It presses John’s arse into his trousers, sure to leave a wet patch on the fabric, and as Sherlock leans forward and traps John’s cock between their bellies it drools precome onto his shirt.

“You’re getting it all over your clothes. Everyone’s going to know what we did. People will talk.”

“They’d know anyway. Let them.” That’s all the patience that Sherlock has left. He cups John’s chin in his hand to tilt his mouth up and press their lips together. John’s mouth falls open instantly, and Sherlock goes on instinct, tongue darting out to trace John’s thin bottom lip before slipping inside his mouth. John tastes like he smells, sweet and complex, and he’s moaning into the kiss, arching up against Sherlock to rub wantonly against him.

“I need—”

“Will you let me fuck you?” It’s hardly a fair question, given the circumstances, and John’s already said that he wants to spend his heat with him, whatever that entails, but Sherlock needs to ask.

“ _Yes_ ,” John says emphatically. “Yes, fucking _yes_.”

Now both their hands are scrabbling at Sherlock’s clothing, jerking at the buttons of his shirt and fastenings of his trousers until everything is undone and his shirt is pushed off of his shoulders and thrown across the room. Sherlock needs to stand in order to remove the rest of it, but as much as John recognises that particular obstacle, he’s reluctant to release Sherlock from his grip. It takes another kiss, this one more desperate and full of possessive nips—how had Sherlock ever thought that kissing would be boring?—before he can pull himself away from John and shove his clothing down. When he clambers back onto the bed, they’re both gloriously naked, and John feels feverish against him, burning up with the flush of heat on his skin, as Sherlock pulls John’s legs up to wrap them around his waist.

He doesn’t have to tell John to tilt his hips up; John does it instinctually, arching his back and grinding down before Sherlock even has his cock positioned against his entrance. It slides in the considerable slickness between John’s arsecheeks, and, for the first time since this started, Sherlock is the one left gasping.

“C’mon,” John is repeating through every quickening breath, “c’mon, c’mon, _now_.”

Sherlock holds John’s hips steady with one hand and guides his cock with the other. Despite how many fingers he had buried inside of John only moments ago, he meets resistance when he tries to nudge inside and it takes a slow push to work against it.

“Fuck,” John huffs. “Fuck, you’re big, I—”

Is he? He’s never considered it before and—

And his thoughts stop dead because he’s pressed inside; John is parting around him with a relieved cry, and for all that Sherlock is no alpha, his response is all animal craving and need for more, more, nothing else but _this_. The head of his cock drags against John’s prostate on the slow and steady push towards the place where John needs him most. It rips a startled noise from John’s lips; his back bows and thighs clamp down over the crests of Sherlock’s hips, and then Sherlock’s _there_ , sinking into clenching, searing heat.

When his pelvis is flush against John he stills, overwhelmed. He’s never—he’s never even _come_ before, and suddenly he’s inside of an omega in heat— _John_ in heat; extraordinary, wonderful, brilliant John—

It all goes in a bit of a blur after that. John is panting, mumbling under his breath, “Fuck me, fuck, fuck” and staring at Sherlock wide-eyed like he’s done something fantastic. John’s legs find their way to Sherlock’s shoulders and his hips tilt up; Sherlock’s going deeper and John is shaking now, sounds like he might even be sobbing, so Sherlock soothes him by catching his face in his hands, stroking his thumbs over his cheeks, and pulling him into a kiss. Impossible to tell exactly how long it goes on like this—Sherlock’s never been so incapable of thought or awareness, _never_ —but it feels like an unfathomable age and mere minutes at the same time when John shudders and cries out and Sherlock can feel him spurting between them along with the desperate clamp of John’s internal muscles around him. It explodes something inside of Sherlock, shakes loose a feeling he didn’t even realise was possible, and his brain grasps that he’s coming as well, buried as far inside of John as he can reach.

Sherlock’s nervous system is on fire, tingling through every inch of his skin. He wants nothing more than to roll away and process all of it, but when he tries, John grabs him hard enough to bruise.

“No, you can’t. Your knot—” John sounds frantic. “You don’t have a knot, oh _hell_ ; there’s nothing to keep it in—” Sherlock is just about to ask what he’s going on about when John’s fingers move clumsily between them to the rim of his entrance where it’s still stretched around Sherlock’s cock and press in alongside. Just the tips, because that’s as far as John can reach, but it’s enough to make both of them moan. Sherlock can feel his come leaking down the curve of John’s arse and onto his own thighs and it’s filthy. Filthy and hot and yet another thing he hadn’t considered at all before today.

“John,” Sherlock gasps, “it’s an irrational response. I couldn’t even—I’m not an alpha.”

John jerks his fingers away, and even through the sex-flush on John’s face Sherlock can see that he’s coloured, embarrassed about letting his instincts take over. “Yeah—yeah, I know. It’s all irrational and a fucking mess.” He lets his legs slip from Sherlock’s shoulders, winces when they pull apart. “My brain is yelling at me, telling me to push a bunch of spunk inside myself so I can get knocked up, and having you see this—all of this—is humiliating.” John bites his lip and looks away.

“I’m not judging you for it.”

“No, I don’t think you would.” John frowns, looks down at himself with disgust. He’s a mess; they both are. “I can’t believe I asked you to do that. You’ve never even—”

“Don’t,” Sherlock cuts him off. “I wanted to. You didn’t trick me or take advantage of me, or any of the awful things some people say about omegas. I did this because you are my friend.” If they were still in the throes of heat Sherlock might kiss him again to reassure him. Might kiss him again just to feel it. He’s not sure if it’s acceptable to John when his mind is clear, so he refrains.

“It’s all fine?” John asks quietly.

“It’s all fine.”


End file.
